Relationship between physical performance and self-reported function in healthy individuals across the lifespan

Background: Functional outcome measures in clinical trials of musculoskeletal conditions need to be meaningful to individuals. Objectives: To investigate the relationship between physical performance and self/proxy-reported function in 1000 healthy children and adults. Design: Cross-sectional observational study (1000 Norms Project). Methods: One thousand males and females aged 3–101 years, healthy by self-report and without major physical disability, were recruited. Twelve performance-based tests were analysed: vertical and long jump, two hand dexterity tests, four balance tests, stepping reaction time, 30-second chair stand, timed up-and-down stairs, and six-minute walk. Self/proxy-reported function was assessed using the Infant-Toddler Quality of Life questionnaire, Child Health Questionnaire, Assessment of Quality of Life (AQoL)-6D Adolescent, AQoL-8D, International Physical Activity Questionnaire and work ability question. Bivariate and multivariate correlational analyses were constructed for infants (3-4y), children (5-10y), adolescents (11-17y), adults (18-59y) and older adults (60+). Results/findings: Socio-demographic characteristics were similar to the Australian population. Among infants/children, greater jump and sit-to-stand performance correlated with higher proxy-reported function (p < 0.05). There were no significant relationships observed for adolescents (p > 0.05). Greater jump, dexterity, balance, reaction time, sit-to-stand, stair-climbing and six-minute walk performance correlated with higher self-reported function in adults (r = −0.097 to.231; p < 0.05) and older adults (r = −0.135 to 0.625; p < 0.05). Multivariate regression modelling revealed a collection of independent performance measures explaining up to 46% of the variance in self/proxy-reported function. Conclusions: Many performance-based tests were significantly associated with self/proxy-reported function. We have identified a set of physical measures which could form the basis of age-appropriate functional scales for clinical trials of musculoskeletal conditions.